The present disclosure relates to an ion injection simulation method based on a well proximity effect, an ion injection simulation device, a method of producing a semiconductor device, and a method of designing a semiconductor device.
As a simulation method of an ion injection process used in a process of producing a semiconductor device, an analytical model is used. In the analytical model, impurity concentration distribution based on ion injection is approximated using a distribution function such as a dual-Pearson IV type function (for example, see Changhae Parka, Kevin M. Kleina and Al F. Tascha, “Efficient modeling parameter extraction for dual Pearson approach to simulation of implanted impurity profiles in silicon”, Solid-State Electronics, Volume 33, Issue 6, June 1990, Pages 645-650).
In the process of producing the semiconductor device, high energy and a large amount of ions are necessary in a well forming process. For this reason, of the thickness of a mask resist for preventing ion injection increases. The ions injected into the mask resist at the time of well forming are dispersed in the resist. Particularly, there is possibility that the ions appear from a side face of the mask resist by the dispersion of the ions in the transverse direction. For this reason, in an area of a substrate which is not covered with the resist, unintended impurity distribution is formed by the appearance of the ions from the side face of the mask resist. This is a primary factor in causing fluctuations in a device such as a threshold value of a transistor. This phenomenon is called a well proximity effect.
In the production of a semiconductor device, it is proposed to optimize a design of a device to alleviate fluctuations in a device caused by the well proximity effect described above (for example, see Japanese Unexamined Patent Application Publication No. 2008-177518).